Research on the mathematical model of oil‑tea tree age

Tree age influences on the yield of oil-tea seeds and the quality of tea oil， to nondestructively measure the age of old oil-tea tree， a mathematical model between the age of old oil-tea tree and the ground diameter of the ground was established. First， the age and ground diameter of each harvested oil-tea tree were measured， and then 2/3 of the data were used as the modeling data set to establish the linear， logarithmic， exponential， and hybrid models between age and ground diameter， respectively， and finally， the remaining 1/3 of the data were used as the testing data set to test the prediction accuracy for these four mathematical models. The adjusted coefficients of determination for the linear， logarithmic， exponential and mixed models were 0.756， 0.769， 0.661 and 0.787， respectively， and the average prediction accuracies were 83.379%， 83.441%， 78.207% and 84.878%， with the prediction standard deviations being 5.441 a， 6.826 a， 6.843 a and 5.898 a， respectively. The results showed that， among these four models， the hybrid model exhibited the best fit and the highest prediction accuracy.